code: def save_variable_list(variables):
      names = [k for k, _ in variables.items()]
      with open(os.path.join(CACHE_FOLDER, "cache_info.csv"), "w") as f:
          for line in names:
              f.write(line + "\n")
  
file_path: nnabla/src/nbla_utils/test/test_npy_files.py
imports: import pytest
  import numpy
  import zlib
  import csv
  import os
  from collections import OrderedDict
label_desc: Use image node_id 1 for calling a global function with example usage: save_variable_list(variables) without return types